1. Field of the Invention
The present invention relates to disk refiners and more particularly to improvements in refiner plates and mounting assemblies therefor.
2. Description of the Prior Art
Disk refiners are used in the paper manufacturing industry to prepare the cellulose fibers of a paper pulp into a desired condition prior to delivering the pulp to the papermaking machine. One such refiner is commonly referred to as a double disk refiner, as described in U.S. Pat. No. 4,083,503. In this type of refiner, two refiner plates are attached to opposite sides of a rotating disk, or rotor, and complementary refiner plates are attached to nonrotating elements, or stators. Another type of disk refiner is commonly referred to as a multiple disk refiner as described in U.S. Pat. No. 4,783,014. In this type of refiner, a plurality of rotatable and nonrotatable refiner plates are interleaved within a refining chamber of the refiner. Still another type of refiner is a refiner of the two disk type, commonly referred to as a counter or contra-rotating disk refiner, as described in U.S. Pat. No. 4,129,263. In this type of refiner, two counter-rotating refining disks are located each on a shaft which are driven individually by motors.
The refiner plates in double disk refiners, multiple disk refiners, and counter-rotating disk refiners have a working refining surface usually involving a plurality of raised, rib-like projections, generally called bars. In operation, these bars and other portions of the working surface are gradually abraded or worn away, so that it is periodically necessary to shut down a disk refiner and replace the refiner plates used therein.
There are many different types of refiner plates and refiner plate patterns which are well-known within the paper industry. One type of a refiner plate is a complete annular plate which is cast as a one-piece member. A major disadvantage of this complete annular plate is the high cost associated with fabricating such a plate. Moreover, if only a small section of the plate is worn or damaged, because the replacement plate is a single piece, the entire refiner plate would have to be replaced.
An improvement over the one-piece refiner plate is a refiner plate which comprises a plurality of individual segments which cooperatively form an annular plate when fitted together. The advantages of these segmented plates is the ease of handling, the ease of replacing worn or damaged segments, and they are much less expensive to manufacture than the complete one-piece annular disk.
Just as there are many different types of refiner plates, there are also many different manufacturers that produce these various refiner plates. Additionally, disk refiners come in a variety of different diameters. Typically, disk refiners are of a size to use refiner plates which generally range in diameter from 20 inches to 42 inches. The manner of mounting the refiner plates in the refiner varies from manufacturer to manufacturer. Even a single refiner manufacturer may supply different types of refiners with different plate mounting arrangements. The number, size, and spacing of mounting bolts used varies significantly from manufacturer to manufacturer, and from one size of refiner to another. As a result, because each refiner manufactured by different manufacturers has its own particular mounting pattern to be used in conjunction with that manufacturer's refiner plates, a refiner plate manufacturer supplying refiner plates for several manufacturer's refiners must supply numerous different refiner plates of the same diameter to be used in the many different disk refiners, even if the same bar configuration is used.
Refiner plates like those shown in U.S. Pat. Nos. 4,039,154 and 5,425,508 are typically used in double disk refiners and counter-rotating refiners. These plates are normally cast as a plurality of individual segments which are machined to obtain the desired shape and contours. The segments are assembled to form a complete annular plate. Other refiner plates for other refiners, e.g., multiple disk refiners, and particularly, refiners of smaller diameter, may be fabricated as one-piece plates.
In treating some pulps, low intensity treatment is desirable. It is widely known that low-intensity treatment of certain pulp fiber increases the strength characteristics of the pulp while reducing the amount of specific energy required during refining. As disclosed in U.S. Pat. No. 4,661,911, a reduction in intensity may be accomplished in a refiner having an increased number of refining surfaces. Thus, the multiple disk refiner was a new and improved disk refiner for low intensity treatment of pulp fiber. Still, however, an increase in the number of refining surfaces can further be accomplished by producing a refiner plate with finer bars and grooves than that possible using heretofore accepted processes and designs.